Rotor structure for a turbomachine with venting/sealing arrangement in tie bolt

Abstract

Rotor structure for a turbomachine, such as a centrifugal compressor is provided. Disclosed embodiments make use of venting/sealing arrangements effective for venting a tie bolt rotor so that, for example, an incipient leakage of a process fluid can be monitored. Additionally, in operation disclosed embodiments are effective to, for example, convey to the tie bolt a pressurized sealing fluid effective for reducing the likelihood of process fluid escaping to the atmosphere.

What is claimed is: 
     
       1. A rotor structure for a turbomachine, the rotor structure comprising:
 a tie bolt that extends axially between a pressurized process side and an atmospheric pressure side of the turbomachine; 
 a respective stub shaft fixed to a first end of the tie bolt; 
 a first venting/sealing arrangement comprising: 
 a plurality of axially spaced apart annular seals arranged about a segment of the tie bolt in correspondence with a radially-inward segment of the respective stub shaft, wherein each respective neighboring seal pair of the plurality of axially spaced apart annular seals defines sealing sides of a respective chamber of a plurality of axially sequential chambers disposed between the process side and the atmospheric pressure side of the turbomachine; and 
 a plurality of conduits extending from a radially-outward segment of the respective stub shaft through the stub shaft to communicate with the plurality of axially sequential chambers disposed between the process side and the atmospheric pressure side of the turbomachine, the plurality of conduits alternating between a first conduit fluidly coupled at the radially-outward segment of the respective stub shaft to receive a sealing fluid and a second conduit fluidly connected at the radially-outward segment of the respective stub shaft for venting, 
 wherein, in response to flow of an incipient leakage of a process fluid through one or more of the plurality of axially spaced apart annular seals, a first fluid flow is established through the first conduit to convey sealing fluid into the respective chamber in communication with the first conduit, and/or a second fluid flow is established through the second conduit to permit venting of the respective chamber in communication with the second conduit. 
 
     
     
       2. The rotor structure of  claim 1 , wherein the plurality of axially sequential chambers disposed between the process side and the atmospheric pressure side of the turbomachine define a sequence of alternating chambers between a first chamber arranged to receive sealing fluid and a second chamber arranged to vent the incipient leakage of the process fluid. 
     
     
       3. The rotor structure of  claim 2 , wherein the plurality of axially-sequential chambers includes at least one backup first chamber relative to a first chamber disposed downstream of the at least one backup first chamber and at least one backup second chamber relative to a second chamber disposed downstream of the at least one backup second chamber, wherein the first chamber and the backup first chamber is each independently arranged to receive sealing fluid, and wherein the second chamber and the backup second chamber is each independently arranged to permit venting. 
     
     
       4. The rotor structure of  claim 1 , wherein a dry fluid seal system disposed about the radially-outward segment of the respective stub shaft comprises a source of the sealing fluid and a venting outlet for the incipient leakage of the process fluid. 
     
     
       5. The rotor structure of  claim 1 , wherein the first end of the tie bolt corresponds to the pressurized process side of the turbomachine. 
     
     
       6. The rotor structure of  claim 1 , further comprising a second stub shaft fixed to a second end of the tie bolt, the second end being axially opposite to the first end of the tie bolt;
 a second venting/sealing arrangement comprising: 
 a further plurality of axially spaced apart annular seals arranged about a segment of the tie bolt in correspondence with a radially-inward segment of the second stub shaft, wherein each respective neighboring seal pair of the further plurality of axially spaced apart annular seals defines sealing sides of a respective chamber of a further plurality of axially sequential chambers disposed between the process side and the atmospheric pressure side of the turbomachine; and 
 a further plurality of conduits extending from a radially-outward segment of the second stub shaft through the second stub shaft to communicate with the further plurality of axially sequential chambers disposed between the process side and the atmospheric pressure side of the turbomachine, the further plurality of conduits alternating between a first conduit fluidly coupled at the radially-outward segment of the second stub shaft to receive further sealing fluid and a second conduit fluidly connected at the radially-outward segment of the second stub shaft for venting, 
 wherein, in response to flow of a further incipient leakage of the process fluid through one or more of the further plurality of axially spaced apart annular seals, a first fluid flow is established through the first conduit of the further plurality of conduits to convey the further sealing fluid into the respective chamber of the further plurality of axially sequential chambers in communication with the first conduit, and a second fluid flow is established through the second conduit of the further plurality of conduits connected to permit venting of the respective chamber in communication with the second conduit. 
 
     
     
       7. The rotor structure of  claim 6 , wherein the second end of the tie bolt corresponds to the atmospheric pressure side of the turbomachine. 
     
     
       8. The rotor structure of  claim 6 , further comprising a plurality of impeller stages disposed between the stub shafts, the plurality of impeller stages supported by the tie bolt. 
     
     
       9. The rotor structure of  claim 8 , further comprising respective joint structures arranged to couple contiguous impeller stages to one another. 
     
     
       10. The rotor structure of  claim 9 , wherein the respective joint structures comprise respective Hirth joint structures. 
     
     
       11. The rotor structure of  claim 1 , further comprising a computerized leakage monitor coupled to the second conduit to monitor a presence of the incipient leakage of the process fluid. 
     
     
       12. A centrifugal compressor comprising the rotor structure of  claim 1 .